The demand for computing devices continues to rise, even as the demand for computing devices to achieve higher performance also rises. However, conventional electrical I/O (input/output) signaling is not expected to keep pace with the demand for performance increases, especially for future high performance computing expectations. Currently, I/O signals are sent electrically from the processor (e.g., CPU—central processing unit) through the processor package (or just package), socket (which is sometimes not present), and board to electrical cables and/or backplanes. Electrical signals must pass through one or more levels of solder joints, traces, cables, and other electrical conductors. Electrical I/O signal rates are limited by the electrical characteristics of the electrical connectors, package, and board traces. In addition, the need for equalization and the high losses of package and board traces and connectors result in poor scaling of energy per bit.
While the use of photonic components finds increasing use in computing devices, current optical signaling solutions are not scalable to the level needed to access the potential advantages of optical communication. The use of optical signals in device communication has significant potential advantages over electrical communication, namely in terms of power and theoretical bandwidth at distances greater than 1 m. However, the inability to scale the solutions prevents current optical interconnect systems from meeting the requirements of many high performance computing applications.
An alternative to electrical signaling in use today is based on optical cables that receive an electrical signal and convert it to optical. Such cables transfer optical signaling that terminates far from the processor, which requires electrical-optical conversion and electrical transfer that creates a bottleneck to the processor. Serial connections to the processor are too slow to take advantage of the optical signaling throughput capabilities, and parallel connections to the processor require a significant amount of board real estate and pins to the processor package. In addition, the current components used in the optical signaling and electrical-optical coupling do not scale in a way that is usable with high-volume manufacturing. Currently, there are no optical connectors that can provide the form factor needed or the two-dimensional scalability and manufacturability needed with sufficiently low optical loss to enable closer optical termination.
Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.